Jammer Selection And Power Allocation In Secure Two-Way Wireless Cooperative Communication System

In wireless communication systems,the broadcast characteristics of wireless channel makes the transferred information can be easily eavesdropped by illegal users,which lead to information leakage and poses serious threats to the security of wireless communication systems.In this dissertation,jammer selection and power allocation are studied from the aspect of security in wireless communication system,and the specific work is as follows:A power allocation scheme for amplify-and-forward cooperative wireless communication system with untrusted relay is studied.In the case that the total power of each node is limited in the two-way untrusted relay communication system,a security strategy is proposed,where source nodes allocate a part of power to transmit useful signal and the rest to transmit jamming signal to confuse the untrusted relay.The jamming signal can be decoded not by the untrusted relay but only by the source nodes.An optimal power allocation scheme based on global channel state information is proposed to maximize the system security capacity,and it is compared with the non-jamming scheme that source nodes do not transmit the jamming signal.An expression of the optimal power distribution factor between useful signal and jamming signal is derived.Simulation results demonstrate that the security performance of the optimal power allocation scheme is better than that of the nonjamming scheme,which implies the expression of the optimal power allocation factor is correct.The influence of power allocation and jammer selection on the security performance in the secure two-way decoded-and-forward communication system is studied.In the case that the total power of each communication stage is limited,the artificial noise generated by the friendly jammer can be eliminated by the legitimate users and it only affects the eavesdropper.A new joint jammer selection and power allocation scheme is proposed to maximize the secrecy capacity of the wireless cooperative communication system.The optimal expressions for the optimal power distribution factor and the optimal jamming node selection are obtained,respectively.Simulation analysis verifies the correctness of the expressions and the validity and advantages of the discussed scheme.